Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D405/00—Heterocyclic compounds containing both one or more hetero rings having oxygen atoms as the only ring hetero atoms, and one or more rings having nitrogen as the only ring hetero atom
  • C07D405/02—Heterocyclic compounds containing both one or more hetero rings having oxygen atoms as the only ring hetero atoms, and one or more rings having nitrogen as the only ring hetero atom containing two hetero rings
  • C07D405/04—Heterocyclic compounds containing both one or more hetero rings having oxygen atoms as the only ring hetero atoms, and one or more rings having nitrogen as the only ring hetero atom containing two hetero rings directly linked by a ring-member-to-ring-member bond
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D311/00—Heterocyclic compounds containing six-membered rings having one oxygen atom as the only hetero atom, condensed with other rings
  • C07D311/02—Heterocyclic compounds containing six-membered rings having one oxygen atom as the only hetero atom, condensed with other rings ortho- or peri-condensed with carbocyclic rings or ring systems
  • C07D311/04—Benzo[b]pyrans, not hydrogenated in the carbocyclic ring
  • C07D311/58—Benzo[b]pyrans, not hydrogenated in the carbocyclic ring other than with oxygen or sulphur atoms in position 2 or 4
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D311/00—Heterocyclic compounds containing six-membered rings having one oxygen atom as the only hetero atom, condensed with other rings
  • C07D311/02—Heterocyclic compounds containing six-membered rings having one oxygen atom as the only hetero atom, condensed with other rings ortho- or peri-condensed with carbocyclic rings or ring systems
  • C07D311/04—Benzo[b]pyrans, not hydrogenated in the carbocyclic ring
  • C07D311/58—Benzo[b]pyrans, not hydrogenated in the carbocyclic ring other than with oxygen or sulphur atoms in position 2 or 4
  • C07D311/68—Benzo[b]pyrans, not hydrogenated in the carbocyclic ring other than with oxygen or sulphur atoms in position 2 or 4 with nitrogen atoms directly attached in position 4
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D405/00—Heterocyclic compounds containing both one or more hetero rings having oxygen atoms as the only ring hetero atoms, and one or more rings having nitrogen as the only ring hetero atom
  • C07D405/14—Heterocyclic compounds containing both one or more hetero rings having oxygen atoms as the only ring hetero atoms, and one or more rings having nitrogen as the only ring hetero atom containing three or more hetero rings

Definitions

• the present invention relates to novel benzopyrans having pharmacological activity, to a process and intermediates for preparing them, to pharmaceutical compositions containing them, and to their use in the treatment of mammals.
• European Patent Publications 76075, 93535, 95316, 107423, 120427, 126311, 126350, 126367 and 138134 disclose classes of compounds that are described as having blood pressure lowering activity or anti-hypertensive activity.
• a class of compounds has now been discovered which are 4-substituted benzopyrans substituted in the 6-position by an alkyl group.
• benzopyrans have been found to have blood pressure lowering activity, useful in the treatment of hypertension.
• these compounds are believed to be K + channel activators which indicates that they are of potential use in the treatment of disorders associated with smooth muscle contraction of the gastro-intestinal tract, respiratory system, uterus or urinary tract.
• disorders include irritable bowel syndrome and diverticular disease, reversible airways obstruction and asthma; premature labour; and incontinence.
• cardiovascular disorders other than hypertension, such as congestive heart failure, angina, peripheral vascular disease and cerebral vascular disease.
• the present invention provides a compound of formula (I) or, when the compound of formula (I) contains a salifiable group, a pharmaceutically acceptable salt thereof: ##STR2## wherein: Y is N or (when R 3 is hydroxy, C 1-6 alkoxy or C 1-7 acyloxy) CH;
• R 1 and R 2 are hydrogen or C 1-4 alkyl and the other is C 1-4 alkyl or R 1 and R 2 together are C 2-5 -polymethylene;
• R 3 is hydrogen, hydroxy, C 1-6 alkoxy or C 1-7 acyloxy
• R 4 is a C 3-8 cycloalkyl group or a C 1-6 alkyl group optionally substituted by a group R 7 which is hydroxy, C 1-6 alkoxy, amino optionally substituted by one or two C 1-6 alkyl groups; C 1-7 alkanoylamino, C 3-8 -cycloalkyloxy, C 3-8 cycloalkylamino, or 1,3-dioxo-2-isoindoline;
• R 5 is hydrogen, C 1-6 alkyl optionally substituted by halogen, hydroxy, C 1-6 alkoxy, C 1-6 alkoxycarbonyl, carboxy or amino optionally substituted by one or two independent C 1-6 alkyl groups, or C 2-6 alkenyl, amino optionally substituted by a C 1-6 alkyl, C 3-8 cycloalkyl or C 1-6 alkenyl group or by a C 1-6 alkanoyl group optionally substituted by up to three halo atoms, by a phenyl group optionally substituted by C 1-6 alkyl, C 1-6 alkoxy or halogen, or aryl or heteroaryl, either being optionally substituted by one or more groups or atoms selected from the class of C 1-6 alkyl, C 1-6 alkoxy, hydroxy, halogen, trifluoromethyl, nitro, cyano, C 1-12 carboxylic acyl, or amino or aminocarbonyl optionally substituted by one or
• R 5 is NR 8 R 9 wherein R 8 and R 9 are independently C 1-6 alkyl, R 8 is hydrogen and R 9 is C 1-6 alkyl or R 8 and R 9 together are C 4-5 polymethylene; or R 6 and R 8 together are --(CH 2 ) p -- wherein p is 2 or 3, and R 9 is hydrogen or C 1-6 alkyl; or R 5 is CH 2 R 10 wherein R 10 is hydrogen or C 1-5 alkyl; or R 6 and R 10 are --(CH 2 ) q -- wherein q is 2 or 3;
• X is oxygen or sulphur
• R 5 , R 6 , X and Y (when N) together are tetrahydroisoquinolinone or tetrahydroisoquinolinthione, optionally substituted in the phenyl ring as defined for R above; the nitrogen-containing group in the 4-position being trans to the R 3 group when R 3 is hydroxy, C 1-6 alkoxy or C 1-7 acyloxy.
• Y is preferably N.
• R 1 and R 2 are both C 1-4 alkyl, in particular both methyl.
• R 3 is C 1-6 alkoxy
• preferred examples of R 3 include methoxy and ethoxy, of which methoxy is more preferred.
• R 3 is C 1-7 acyloxy a preferred class of R 3 is unsubstituted carboxylic acyloxy, such as unsubstituted aliphatic acyloxy. However, it is more preferred that R 3 is hydroxy.
• R 4 examples include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, methyl, ethyl, n- and iso-propyl, n-, iso-, sec- and tert-butyl, optionally substituted by a group R 7 1 which is hydroxy, C 1-4 alkoxy, amino optionally substituted by one or two C 1-4 alkyl groups, C 1-5 alkanoylamino, C 5-7 cycloalkyloxy or C 5-7 cycloalkyl.
• C 1-4 alkyl groups in R 7 1 may be methyl, ethyl, n- or iso-propyl, n-, iso-, sec-, or tert-butyl.
• C 5-7 cycloalkyl groups in R 7 1 may be cyclopentyl, cyclohexyl or cycloheptyl.
• R 4 is preferably C 5-7 cycloalkyl or C 1-4 alkyl.
• R 5 when C 1-6 alkyl, include methyl, ethyl, and n- and iso-propyl. Preferably such R 5 is methyl.
• a sub-group of R 5 when C 1-6 alkyl substituted by halogen is C 1-6 alkyl substituted by chloro or bromo. Examples thereof include methyl or ethyl terminally substituted by chloro or bromo.
• R 5 when C 1-6 alkyl substituted by hydroxy, include methyl or ethyl terminally substituted by hydroxy.
• a sub-group of R 5 when C 1-6 alkyl substituted by alkoxy is C 1-6 alkyl substituted by methoxy or ethoxy. Examples thereof include methyl or ethyl terminally substituted by methoxy or ethoxy.
• a sub-group of R 5 when C 1-6 alkyl substituted by C 1-6 alkoxycarbonyl is C 1-6 alkyl substituted by methoxycarbonyl or ethoxycarbonyl. Examples thereof include methyl or ethyl terminally substituted by methoxycarbonyl or ethoxycarbonyl.
• R 5 when C 1-6 alkyl substituted by carboxy include methyl or ethyl terminally substituted by carboxy.
• R 5 when alkyl substituted by amino optionally substituted by one or two independent C 1-6 alkyl groups include a group (CH 2 ) r NR a R b where r is 1 to 6, and R a and R b are each independently hydrogen or C 1-6 alkyl. Examples of r include 1 and 2, in particular 1. Preferably R a and R b are each independently selected from hydrogen and methyl.
• R 5 when C 2-6 alkenyl include vinyl, prop-1-enyl, prop-2-enyl, 1-methylvinyl, but-1-enyl, but-2-enyl, but-3-enyl, 1-methylenepropyl, or 1-methylprop-2-enyl, in both their E and Z forms where stereoisomerism exists.
• R 5 when amino optionally substituted as hereinbefore defined include amino optionally substituted by a C 1-4 alkyl group as described for R 7 1 , an allyl or trichloroacetyl group or by a phenyl group optionally substituted by one methyl, methoxy or chloro group or atom, in particular amino, methylamino, and phenylamino optionally substituted in the phenyl ring by one methyl, methoxy or chloro group or atom.
• R 5 when aryl include phenyl and naphthyl, of which phenyl is preferred.
• a sub-group of R 5 heteroaryl or heteroaryl in a Z moiety when NR is 5- or 6-membered monocyclic or 9- or 10-membered bicyclic heteroaryl of which 5- or 6-membered monocyclic heteroaryl is preferred.
• 5- or 6-membered monocyclic or 9- or 10-membered bicyclic heteroaryl preferably contains one, two or three heteroatoms which are selected from the class of oxygen, nitrogen and sulphur and which, in the case of there being more than one heteroatom, are the same or different.
• Examples of 5- or 6-membered monocyclic heteroaryl containing one, two or three heteroatoms which are selected from the class of oxygen, nitrogen and sulphur include furyl, thienyl, pyrryl, oxazolyl, thiazolyl, imidazolyl and thiadiazolyl, and pyridyl, pyridazyl, pyrimidyl, pyrazyl and triazyl.
• Preferred examples of such groups include furanyl, thienyl, pyrryl and pyridyl, in particular 2- and 3-furyl, 2- and 3-pyrryl, 2- and 3-thienyl, and 2-, 3- and 4-pyridyl.
• 9- or 10-membered bicyclic heteroaryl containing one, two or three heteroatoms which are selected from the class of oxygen, nitrogen and sulfur include benzofuranyl, benzothienyl, indolyl and indazolyl, quinolyl and isoquinolyl, and quinazonyl.
• Preferred examples of such groups include 2- and 3-benzofuryl, 2- and 3-benzothienyl, and 2- and 3-indolyl, and 2- and 3-quinolyl.
• the number of groups or atoms for optional substitution of aryl or heteroaryl is one, two, three or four.
• Preferred examples of the groups or atoms for optional substitution of aryl or heteroaryl include methyl, methoxy, hydroxy, bromo, chloro, fluoro, nitro or cyano.
• a sub-group of R 5 is phenyl or naphthyl or a 5- or 6-membered monocyclic or a 9- or 10-membered bicyclic heteroaryl, the phenyl, naphthyl or heteroaryl group being optionally substituted by one, two, three or four groups or atoms selected from the class of C 1-6 alkyl, C 1-6 alkoxy, halogen, (such as chloro, bromo or, in particular, fluoro), trifluoromethyl, nitro or cyano.
• halogen such as chloro, bromo or, in particular, fluoro
• phenyl optionally substituted as hereinbefore defined is phenyl, 4-substituted phenyl, 3-substituted phenyl, 3,4-disubstituted phenyl and 3,4,5-trisubstituted phenyl.
• a preferred sub-group of 5- or 6-membered monocyclic or 9- or 10-membered bicyclic heteroaryl optionally substituted as hereinbefore defined is unsubstituted or mono-substituted 5- or 6-membered monocyclic or 9- or unsubstituted 5- or 6-membered monocyclic or 9- or 10-membered bicyclic heteroaryl.
• R 5 and R 6 when together are --CH 2 --(CH 2 ) n --Z--(CH 2 ) m -- as defined the resulting radical substituting the benzopyran in the 4-position is preferably either pyrrolidonyl or piperidonyl.
• R When Z is other than CH 2 , m is often 0 or 1 and n is often 0 or 1.
• Suitable examples of R when Z is NR include hydrogen, methyl, ethyl, n- and iso-propyl, n-, iso-, sec- and tert-butyl, benzyl, phenylcarbonyl or benzylcarbonyl optionally substituted in the phenyl ring by methyl, methoxy, chloro or bromo; furylcarbonyl, thienylcarbonyl, pyrrolylcarbonyl or indolylcarbonyl.
• R is hydrogen, methyl, n-butyl, acetyl, benzyl, benzylcarbonyl, phenylcarbonyl or furylcarbonyl. Most preferably R is methyl.
• R 5 and R 6 are R 5 methyl and R 6 hydrogen and R 5 and R 6 together are C 3 or C 4 polymethylene.
• R 6 is preferably hydrogen and R 5 is NR 8 R 9 .
• R 8 and R 9 include hydrogen (for R 8 ), methyl, ethyl, n- and iso-propyl, and n-, iso-, sec- and t-butyl, C 4 or C 5 polymethylene or R 8 together with R 6 is --(CH 2 ) 2 -- or --(CH 2 ) 3 --, and R 9 is hydrogen or an alkyl group as described above.
• R 8 and R 9 are each methyl or R 6 CHCXNR 8 R 9 forms a pyrrolidone or piperidone ring and R 9 is methyl.
• X is oxygen
• Examples of a pharmaceutically acceptable salt of a compound of formula (I), when the compound contains a salifiable group which is an optionally substituted amino group, include acid addition salts such as the hydrochloride and hydrobromide salts. Such a salifiable group may be within an R 4 or R 5 group. A carboxy group within R 5 may also be salifiable to form metal salts, such as alkali metal salts, or optionally substituted ammonium salts.
• the compounds of formula (I) may also exist as hydrates and these are included wherever a compound of formula (I) or a salt thereof is herein referred to.
• the present invention extends to all such isomers individually and as mixtures, such as racemates.
• Examples of compounds of formula (I) include the compounds prepared in the Examples hereinafter.
• the present invention also provides a process for the preparation of a compound of formula (I) or, when the compound of formula (I) contains a salifiable group, a pharmaceutically acceptable salt thereof, which comprises;
• L 1 is a leaving group
• R 11 is hydrogen, C 1-6 alkyl optionally substituted by halogen, hydroxy, C 1-6 alkoxy, C 1-6 alkoxycarbonyl, carboxy or amino optionally substituted as hereinbefore defined for R 5 , C 2-6 alkenyl or optionally substituted aryl or heteroaryl as hereinbefore defined for R 5 , or a group convertible to R 5 as hereinbefore defined, and thereafter, when R 6 is hydrogen and R 11 is Q(CH 2 ) z --, where z is 3 or 4; and Q is a leaving group, cyclising the resultant compound;
• R 12 is hydrogen, C 1-6 alkyl, C 1-6 alkenyl, C 1-6 alkanoyl optionally substituted by up to three halo atoms, or phenyl optionally substituted by C 1-6 alkyl, C 1-6 alkoxy or halogen; and X is oxygen or sulphur, and thereafter when R 12 is hydrogen, optionally converting R 12 ; or (ii) where, in the resultant compound of formula (I), Y is N and R 5 and R 6 are joined together, or Y is CH, reacting a compound of formula (V): ##STR4## wherein R 4 ', R 1 and R 2 are as hereinbefore defined, with a compound of formula (VI):
• R 13 and R 14 together are --CH 2 --(CH 2 ) n --Z--(CH 2 ) m -- or R 14 YHCOR 13 is tetrahydroisoquinolinone; or (when Y is CH) R 13 is NR 8 'R 9 or CHR 10 CO 2 R 15 wherein R 15 is C 1-6 alkyl or benzyl, R 8 ' is R 8 or an amino protecting group and the remaining variables are as hereinbefore defined; and thereafter, if necessary, converting R 13 to R 7 , converting R 8 ' to R 8 ; optionally converting R 3 in the resulting compound into another R 3 ; converting R 4 ' to R 4 and optionally thiating the R 6 --Y--CO--R 5 group in the resulting compound to give a compound wherein X is sulphur; and when the resulting compound of formula (I) contains a salifiable group, optionally forming
• the leaving group L 1 is a group that is displaceable by a primary or secondary amino nucleophile. Examples of such a group include C 1-4 alkanoyloxy, and halogen, such as chloro and bromo.
• the acylating agent of formula (III) is either an acid anhydride or an acid halide. When it is an acid anhydride, it may be a mixed or simple anhydride. If it is a mixed anhydride, it may be prepared in situ from a carboxylic acid and an acid halide, although this is less preferred than using the halide itself.
• R 5 in the desired compound of formula (I) is an R 5 optionally substituted amino-substituted alkyl group as hereinbefore defined
• R 11 is a group convertible to the R 5 substituted alkyl group as hereinbefore defined, in particular that it is C 1-6 alkyl substituted by halo, especially bromo.
• the R 11 halo substituent in the resultant compound of process variant (i) (a) may be converted to an R 5 substituent which is amino optionally substituted as hereinbefore defined by a conventional amination reaction with ammonia or a corresponding alkyl- or dialkylamine.
• R 11 may be C 1-6 alkyl substituted by protected amino, protected C 1-6 alkylamino or amino substituted by two independent C 1-6 alkyl groups, it being necessary to protect the R 11 amino function in process variant (i) (a).
• the acylation of the compound of formula (II) may be carried out in the presence of an acid acceptor, such as sodium acetate, optionally using the anhydride as the solvent.
• an acid acceptor such as sodium acetate
• the acylation of the compound of formula (II) is, preferably, carried out in a non-aqueous medium, such as dichloromethane, in the presence of an acid acceptor, such as triethylamine, trimethylamine, pyridine, picoline or calcium, potassium or sodium carbonate.
• a non-aqueous medium such as dichloromethane
• an acid acceptor such as triethylamine, trimethylamine, pyridine, picoline or calcium, potassium or sodium carbonate.
• R 3 in a compound of formula (II) is hydroxy
• the reaction may be carried out under controlled conditions such that only the R 6 1 YH-- is acylated, for example, by using a C 2-9 acyloxy group as the leaving group L 1 , in the acylating agent of formula (III) in the manner as previously described for an acid anhydride, and/or effecting the reaction at relatively low temperature, e.g. at below 10° C.
• R 3 may be C 1-7 acyloxy in a compound of formula (II), although less preferably if R 3 in the resultant compound of formula (I) is to be hydroxy, and, after reaction with the acylating agent of formula (III), be converted into hydroxy, as described hereinafter.
• R 9 is Q(CH 2 ) z where the variables are as hereinbefore defined, the leaving group Q is a group that is displaceable by a secondary amino nucleophile adjacent to a carbonyl function.
• a preferred example is chloro.
• reaction between the compounds of formulae (II) and (IV) is, preferably, carried out in a solvent, such as methylene chloride, at below room temperature, in particular below 10° C.
• reaction between the compounds of formulae (II) and (IV) is, preferably, carried out using a corresponding alkali metal cyanate or thiocyanate, for example that of sodium or potassium, in an optionally methanolic aqueous medium acidified with a mineral acid, such as dilute hydrochloric acid.
• a slightly elevated temperature such as 50° to 90° C. is apt.
• reaction of a compound of formula (V) with a compound of formula (VI) it is particularly preferred that the reaction is carried out under basic conditions so as to facilitate the formation of the anion of the compound of formula (VI), for example, in the presence of sodium hydride.
• the reaction is preferably carried out in a solvent such as tetrahydrofuran at a temperature of -70° C. to reflux, depending on the anion of the compound of formula (VI).
• a solvent such as tetrahydrofuran
• the anion is generated by use of a base, such as lithium diisopropylamide.
• An intermediate compound wherein R 13 is CHR 10 CO 2 R 15 may be converted to a compound of formula (I) wherein R 7 is CH 2 R 10 , by deesterification followed by decarboxylation.
• Deesterification may be effected conventionally, the most appropriate method depending to some extent on the nature of the group R 14 .
• basic reaction conditions will generally be applicable.
• the process conditions described hereinafter for the decarboxylation in the presence of base are in general suitable for this deesterification.
• R 14 is, for example, a tert-butyl group
• deesterification may also be effected conventionally in the presence of acid such as trifluoroacetic acid or aqueous hydrochloric acid. Reaction may be effected at ambient temperature or a slightly higher temperature.
• R 14 is for example a benzyl group
• deesterification may also be effected conventionally by hydrogenolysis, for example by transition-metal catalysed hydrogenation, such as that using palladium/charcoal.
• the decarboxylation is conveniently effected by treatment with a moderately strong base optionally in an aqueous reaction medium.
• bases for the reaction include inorganic bases such as sodium hydroxide.
• reaction media include water, usually in admixture with a water-miscible solvent such that the compound is soluble therein.
• aqueous alcohols such as aqueous ethanol and aqueous polyethers such as aqueous dioxan.
• Reaction is conveniently effected at a moderately elevated temperature, such as 50° to 150° C., conveniently at the boiling point of the reaction medium.
• the decarboxylation may be effected by heating to a non-extreme temperature, for example 60° to 150° C. in an inert solvent, such as benzene, toluene or xylene, for example at solvent boiling point.
• a non-extreme temperature for example 60° to 150° C.
• an inert solvent such as benzene, toluene or xylene, for example at solvent boiling point.
• Spontaneous decarboxylation may occur under the reaction conditions for the deesterification. Even where this is not the case, it is convenient to decarboxylate the CHR 10 CO 2 H compound in situ without isolation. It is especially convenient to carry out the conversion CHR 10 CO 2 R 12 to CH 2 R 10 as a single-step one-pot process, by treatment with a moderately strong base optionally in an aqueous reaction medium. Suitable conditions are as hereinbefore described for decarboxylation.
• R 3 when R 3 is hydroxy, it may be alkylated using an alkyl iodide in an inert solvent, such as toluene, in the presence of a base, such as potassium hydroxide, or it may be acylated using a carboxylic acid chloride or anhydride in a non-hydroxylic solvent in the presence of antacid acceptor.
• a base such as potassium hydroxide
• R 3 when R 3 is C 1-7 acyloxy or C 1-6 alkoxy, it may be converted into hydroxy by conventional hydrolysis with, for example, dilute mineral acid.
• Suitable conversions of R 4 '/R 4 include conventional alkylation or acylation of R 7 when hydroxy or optionally monosubstituted amino. It is usually preferred, however, that such conversions are carried out at an earlier stage.
• R 4 ' may be cyano which may be converted to R 4 when a substituted methyl group, by conventional methods as described in the Examples hereinafter, for example, reduction to give an aminomethyl group.
• the optional thiation of the R 6 --Y--CO--R 5 group in a compound of formula (I) to give another compound of formula I, wherein X is sulphur is, preferably, carried out with conventional thiation agents, such as hydrogen sulphide, phosporous pentasulphide and Lawesson's reagent (p-methoxyphenylthiophosphine sulphide dimer).
• conventional thiation agents such as hydrogen sulphide, phosporous pentasulphide and Lawesson's reagent (p-methoxyphenylthiophosphine sulphide dimer).
• the use of hydrogen sulphide and phosporous pentasulphide may lead to side-reactions and, therefore, the use of Lawesson's reagent is preferred.
• the thiation reaction conditions are conventional for the thiation agent employed.
• the use of hydrogen sulphide is, preferably, acid catalysed by, for example, hydrogen chloride in a polar solvent, such as acetic acid or ethanol.
• the preferred use of Lawesson's reagent is, preferably, carried out under reflux in a dry solvent, such as toluene or methylene chloride.
• a compound of formula (II) wherein R 3 is hydroxy, C 1-6 alkoxy or C 1-7 acyloxy may be prepared by reacting a compound of formula (V), as hereinbefore defined, with a compound of formula (VII):
• R 6 1 is as defined hereinbefore; and optionally converting R 3 hydroxyl in the resulting compound of formula (II) into R 3 when C 1-6 alkoxy or C 1-7 acyloxy.
• the reaction is normally carried out in a solvent, such as a C 1-4 alcohol, in particular methanol, ethanol or propanol at an ambient or an elevated temperature, for example 12° to 100° C.
• a solvent such as a C 1-4 alcohol, in particular methanol, ethanol or propanol
• the reaction proceeds particularly smoothly if carried out in ethanol under reflux.
• the resulting compound of formula (II) may be removed from the reaction mixture by removal of the solvent, for example, by evaporation under reduced pressure. Any epoxide impurity may be removed conventionally, for example by chromatography.
• a compound of formula (II) wherein R 3 is hydrogen may be prepared by known methods, for example as described in Khim. Geterot. Soed 5 (3), 434, 1969.
• a compound of formula (V) may be prepared by reacting a compound of formula (VIII): ##STR5## wherein R 1 and R 2 are as hereinbefore defined, the bromine atom being trans to the hydroxy group, with a base, such as potassium hydroxide, in a solvent, such as ether or aqueous dioxan.
• a compound of formula (VIII) may be prepared by reacting a compound of formula (IX): ##STR6## wherein R 1 and R 2 are as hereinbefore defined, with N-bromosuccinimide in a solvent, such as aqueous dimethyl sulphoxide.
• a compound of formula (IX) may be prepared in accordance with analogous processes to those described in the aforementioned European Patent publications, i.e. by the process depicted below: ##STR7##
• the intermediates of formulae (II) represent part of the present invention.
• the intermediates of formulae (III), (IV), (V), (VI), (VII), (VIII) and (IX) are known or may be prepared in accordance with an appropriate known process.
• the compounds of formula (I) have been found to have blood-pressure lowering activity. They are therefore useful in the treatment of hypertension. They are also believed to be of potential use in the treatment of other disorders hereinbefore referred to.
• the present invention accordingly provides a pharmaceutical composition which comprises a compound of formula (I) or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier.
• the present invention provides an anti-hypertensive pharmaceutical composition which comprises an anti-hypertensive effective amount of a compound of formula (I) or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier.
• compositions are preferably adapted for oral administration. However, they may be adapted for other modes of administration, for example parenteral administration for patients suffering from heart failure. Other alternative modes of administration include sublingual or transdermal administration.
• a composition may be in the form of spray, aerosol or other conventional method of inhalation, for treating respiratory tract disorders.
• compositions may be in the form of tablets, capsules, powders, granules, lozenges, suppositories, reconstitutable powders, or liquid preparations, such as oral or sterile parenteral solutions or suspensions.
• composition of the invention is in the form of a unit dose.
• Unit dose presentation forms for oral administration may be tablets and capsules and may contain conventional excipients such as binding agents, for example syrup, acacia, gelatin, sorbitol, tragacanth, or polyvinylpyrrolidone; fillers, for example lactose, sugar, maize-starch, calcium phosphate, sorbitol or glycine; tabletting lubricants, for example magnesium stearate; disintegrants, for example starch, polyvinylpyrrolidone, sodium starch glycollate or microcrystalline cellulose; or pharmaceutically acceptable wetting agents such as sodium lauryl sulphate.
• binding agents for example syrup, acacia, gelatin, sorbitol, tragacanth, or polyvinylpyrrolidone
• fillers for example lactose, sugar, maize-starch, calcium phosphate, sorbitol or glycine
• tabletting lubricants for example magnesium stearate
• disintegrants for example star
• the solid oral compositions may be prepared by conventional methods of blending, filling or tabletting. Repeated blending operations may be used to distribute the active agent throughout those compositions employing large quantities of fillers. Such operations are of course conventional in the art.
• the tablets may be coated according to methods well known in normal pharmaceutical practice, in particular with an enteric coating.
• Oral liquid preparations may be in the form of, for example, emulsions, syrups, or elixirs, or may be presented as a dry product for reconstitution with water or other suitable vehicle before use.
• Such liquid preparations may contain conventional additives such as suspending agents, for example sorbitol, syrup, methyl cellulose, gelatin, hydroxyethylcellulose, carboxymethylcellulose, aluminium stearate gel, hydrogenated edible fats; emulsifying agents, for example lecithin, sorbitan monooleate, or acacia; non-aqueous vehicles (which may include edible oils), for example almond oil, fractionated coconut oil, oily esters such as esters of glycerine, propylene glycol, or ethyl alcohol; preservatives, for example methyl or propyl p-hydroxybenzoate or sorbic acid; and if desired conventional flavouring or colouring agents.
• suspending agents for example sorbitol, syrup, methyl cellulose,
• fluid unit dosage forms are prepared utilizing the compound and a sterile vehicle, and, depending on the concentration used, can be either suspended or dissolved in the vehicle.
• the compound can be dissolved in water for injection and filter sterilized before filling into a suitable vial or ampoule and sealing.
• adjuvants such as a local anaesthetic, a preservative and buffering agents can be dissolved in the vehicle.
• the composition can be frozen after filling into the vial and the water removed under vacuum.
• Parenteral suspensions are prepared in substantially the same manner, except that the compound is suspended in the vehicle instead of being dissolved, and sterilization cannot be accomplished by filtration.
• the compound can be sterilized by exposure to ethylene oxide before suspending in the sterile vehicle.
• a surfactant or wetting agent is included in the composition to facilitate uniform distribution of the compound.
• compositions may contain from 0.1% to 99% by weight, preferably from 10-60% by weight, of the active material, depending on the method of administration.
• the present invention further provides a method of prophylaxis or treatment of hypertension in mammals including man, which comprises administering to the suffering mammal an anti-hypertensive effective amount of a compound of formula (I) or a pharmaceutically acceptable salt thereof.
• a unit dose form of a composition of the invention may contain from 1 to 100 mg of a compound of the invention and more usually from 1 to 50 mg, for example 1 to 25 mg such as 1, 2, 5, 10, 15 or 20 mg.
• Such compositions may be administered from 1 to 6 times a day, more usually from 1 to 4 times a day, in a manner such that the daily dose is from 1 to 200 mg for a 70 kg human adult and more particularly from 1 to 100 mg.
• the present invention further provides a compound of formula (I) or a pharmaceutically acceptable salt thereof for use in the treatment or prophylaxis of hypertension.
• the epoxide of description 6 (2.5 g) was stirred in ethanol (125 ml) and 0.88 ammonia solution (120 ml) at room temperature for 20 h. The solution was evaporated and partitioned between ethyl acetate and water. The organic layer was washed with brine and dried over anhydrous magnesium sulphate, filtered and evaporated to give the title compound (1.49 g) which was used directly.
• 2-Piperidone (1.0 g) was added to a stirred suspension of sodium hydride (300 mg) in dry dimethylsulphoxide (20 ml) and the mixture stirred for 1 hour, under nitrogen. Then a solution of 6-methyl-3,4-epoxy-3,4-dihydro-2,2-dimethyl-2H-1-benzopyran (1.9 g) in dimethylsulphoxide (10 ml) was added and the mixture stirred for 16 hours, at room temperature. Water was added, and the mixture extracted into ethyl acetate. The combined organic extracts were washed with water, then brine, and dried over magnesium sulphate.
• 2-Pyrrolidone (1.02 g) was added to a suspension of sodium hydride (0.3 g, 80% dispersion in oil) in dry dimethyl sulphoxide (20 ml) under nitrogen at room temperature, and the mixture stirred for 1 h.
• a solution of 3,4-epoxy-3,4-dihydro-2,2,6-trimethyl-2H-1-benzopyran in dry dimethyl sulphoxide (10 ml) was then added, and the reaction mixture stirred for an additional 16 h.
• Cautious addition of water and extraction via ethyl acetate gave a crude product (1.84 g) which was chromatographed on silica gel and eluted with 60°-80° C.
• a solution of lithium diisopropylamine in tetrahydrofuran (20 ml) was prepared at -20° from n-butyl lithium (6.7 ml, 1.5M soln. in hexane) and diisopropylamine (1.4 ml) under N 2 .
• a solution of N,N-dimethylacetamide (0.87 g) in tetrahydrofuran (15 ml) was then added dropwise at -20° C. and the solution stirred for 0.5 h.
• a solution of 3,4-epoxy-3,4-dihydro-2,2,6-trimethyl-2H-1-benzopyran (1.9 g) in tetrahydrofuran (20 ml) was then added at 0° C.
• trans-6-Cyano-3,4-dihydro-2,2-dimethyl-4-(2-oxopyrrolidinyl)-2H-1-benzopyran-3-ol (5 g, prepared as described in J. Med. Chem. 29, 2194 (1986)), in ethanol (375 ml) and glacial acetic acid (75 ml) containing concentrated HCl (5 ml) was shaken in the presence of 10% Pd/C (1 g) in an atmosphere of hydrogen for 4 h. The catalyst was filtered off and the solution neutralised with 10% aqueous NaOH solution, and the solution evaporated to dryness.
• Systolic blood pressures were recorded by a modification of the tail cuff method described by I. M. Claxton, M. G. Palfreyman, R. H. Poyser, R. L. Whiting, European Journal of Pharmacology, 37, 179 (1976).
• a W+W BP recorder, model 8005 was used to display pulses. Prior to all measurements rats were placed in a heated environment (33.5 ⁇ 0.5° C.) before transfer to a restraining cage. Each determination of blood pressure was the mean of at least 6 readings. Spontaneously hypertensive rats (ages 12-18 weeks) with systolic blood pressures >180 mmHg were considered hypertensive.
• the compound of Example 1 gave a maximum fall in blood pressure of 33 ⁇ 2% at a dose of 1.0 mg/kg po.
• Example 13 gave a maximum fall in blood pressure of 54 ⁇ 2% at a dose of 1.0 mg/kg po.
• Other compounds of the Examples, such as E2, E3 and E14 showed significant falls in blood pressure at a dose of 1.0 mg/kg po.

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• 1987
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